The invention relates to a piezoelectric body for an electromechanical transducer comprising a ceramic piezoelectric material.
This type of ceramic material is based on the system PbTiO.sub.3 -PbZrO.sub.3, which system is known from U.S. Pat. No. 2,708,244. A number of improvements have been developed from on this basic system, depending on the intended use of the material, making certain additives to the lead titanate zirconate.
An improved material is inter alia described in U.S. Pat. No. 3,268,453, this material having a composition within the ternary system PbTiO.sub.3 --PbZrO.sub.3 --Pb (Mg.sub.1/3 Nb.sub.2/3)O.sub.3 of the perowskite system. Distinctive features of this material are a relatively high dielectric constant and a high piezoelectric response.
Such a ceramic body, obtained by sintering a starting mixture must be polarised to make it suitable for use as a piezoelectric transducer, that is to say the elementary electric dipoles must be irreversibly oriented in an electric field.
Most known materials of this type have the drawback that polarisation must be effected at an elevated temperature, namely at a temperature between 100.degree. and 200.degree. C., and/or for a long period of time (.degree.1 hour), in an electrically non-conductive oil at a field strength of 1.5-4 MV/m.